ST. LOUIS—The co-founder of the defunct auto service contract seller US Fidelis has been sentenced to eight years in federal prison—more than twice as long as the sentence his brother, the other co-founder, received last week.

Darain Atkinson also was ordered to pay $4 million in restitution at sentencing Tuesday in federal court. He pleaded guilty to state and federal charges in April. His brother, Cory Atkinson, was sentenced to more than three years last week.

Wentzville, Mo.-based US Fidelis misled consumers about what was covered by warranties, lied about affiliation with automakers and dealers and used other deceptive practices. Among other things, prosecutors say the company fraudulently withheld substantial portions of refunds due to customers who canceled vehicle service contracts and were owed full or prorated refunds.